A comparison between two types of central venous catheters in the prevention of catheter-related infections: the importance of performing all the relevant cultures

Objective: to determine the efficacy of double-lumen central venous catheters coated with chlorhexidine and silver-sulfadiazine in reducing the incidence of catheter-related infections. Design: a randomized controlled trial. Setting: medical-surgical intensive care unit of a 600-bed teaching hospital. Patients: adult patients who needed a central venous catheter in the subclavian vein. Intervention: patients received either a standard catheter (n = 46), or a chlorhexidine and silver-sulfadiazine-impregnated catheter (n = 48). Measurements: catheters were removed if there was no need for them anymore or if they were suspected as a cause of infection. Three parts of the catheter were cultured semi-quantitatively. Blood-, wound-, urine- and sputum-cultures were obtained on the day of catheter removal in order to allow a correct diagnosis of catheter-related bloodstream infection (CR-BSI). Results: in total 16 catheters were colonized (17%), six in the antiseptic-bonded catheter group (12%) and 10 in the standard catheter group (22%); relative risk 0.51 (95% CI 0.17-1.65), p = 0.24. After adjustment for potentially confounding factors, relative risk was 0.42 (95% CI 0.12-1.49), p = 0.18. In five out of 16 colonized catheters, there were positive blood cultures with the same microorganism cultured from the catheter as well. In these five patients the diagnosis of CR-BSI was uncertain as in four patients there were other positive cultures with the same micro-organism (from wound, urine or sputum) on the day of catheter removal and in one patient the same micro-organism was already cultured from the blood the day prior to catheter insertion. Conclusion: a protocol in which the catheter is inserted in the subclavian vein results in a low percentage of colonization. There was a trend towards less colonization in the chlorhexidine and silver-sulfadiazine-impregnated catheter group, but this was not statistically significant. In our study-population there were no proven cases of CR-BSI. It is essential to culture wounds, sputum and urine, as well as blood on the day of removal of the catheter to prevent over diagnosis of catheter-related bloodstream infections